1. Field of the Invention
The present invention relates to an optical module holder used in optical fiber communication. In particular, the present invention relates to an optical module holder, an optical module, and an optical connector, in which the optical module is formed integrally with a lens.
2. Description of the Related Art
In recent years, with the increase in the speed and capacity of data communication, the demand for optical fiber communication technology using optical fiber is rising. In such optical fiber communication, the transmitting end converts a signal to be transmitted to an electrical signal. An optical signal formed from light emitted from a light source for communication, such as a semiconductor laser or a light-emitting diode, is transmitted to the receiving end by an optical fiber transmission line, according to the electrical signal. Alight detector receives the transmitted optical signal and converts the optical signal back to the electrical signal. Then, the light detector converts the electrical signal to the required signal. An optical module is used to convert the optical signal delivered by the optical fiber transmission line to the electrical signal or convert the electrical signal to the optical signal and lead the signal out to the optical fiber transmission line in this way. Such an optical module for optical fiber communication includes a photoelectric conversion element package (for example, a package holding a semiconductor light-emitting element, such as a semiconductor laser, or a semiconductor light-receiving element, such as a photo diode), a ferrule that holds the end surface of the optical fiber, a lens that optically joins the photoelectric conversion element within the photoelectric conversion element package and the optical fiber held by the ferrule and makes possible optical communication, and a holder that holds the photoelectric element package, the ferrule, and the lens.
As such an optical module, for example, a following semiconductor element module is proposed (for example, refer to Patent Literature 1). In the semiconductor element module, an engaging section onto which a ferrule for positioning the optical fiber is engaged is formed on one end of a sleeve. An element holding section is formed on the other end of the sleeve on the same axis as the engaging section. A lens holding section is formed between the engaging section and the element holding section. A semiconductor light-emitting element or a light-receiving element is held in the element holding section. A light-collecting lens is held in the lens holding section. However, in this optical module, the semiconductor light-emitting element or light-receiving element, the ferrule, and the lens are separate components. Therefore, when attaching the components to the holder, aligning is required to be performed so that the optical axis of each component matches. The alignment is difficult and, therefore, operating efficiency is poor.
In order to solve this problem, an optically-coupled device module in which the lens and the holder are formed integrally is proposed (for example, refer to Patent Literature 2). In this optical module, it is unnecessary to align the positions of the optical axis of the lens and the axis of the holder. Therefore, the assembly operation of the optical module is facilitated, and the production efficiency of the optical module can be improved.
[Patent Literature 1] Japanese Patent Unexamined Publication No. Heisei 6-300943 (paragraph numbers 0010 and 0018)
[Patent Literature 2] Japanese Patent Unexamined Publication No. Heisei 7-134225 (paragraph numbers 0014 to 0020)
However, as in Patent Literature 2, in the optical module including the holder formed integrally with the lens, the thickness of the holder is uneven. Thin areas are pulled by thick areas due to mold shrinkage, and the holder is unevenly deformed. In particular, the lens area to be the optical path becomes thicker than other areas, increasing the uneven deformation caused by mold shrinkage. As a result, the optical performance of the optical module may be degraded because of such uneven deformation.
In light of such conventional problems, an object of the present invention is to provide an optical module holder that can reduce uneven deformation caused by molding shrinkage, even when the holder and the lens are integrated.